A second mouse to replace keyboard controls for gaming?

Hi! I'm disabled but this post is for my wife. She has carpal tunnel AND De Quervain syndrome in both hands/wrists. Though we're both gamers, and in our forties, we haven't played a "real" computer game is a long time. There's a game she wants to play now, and Diablo 3 is coming. Her problem is that with her wrists she cannot use the keyboard to control a game.

We are wondering if there's some way to use a second mouse on a Windows Vista computer with the second mouse being used in lieu of the wasd/directional arrows. If she could use two mice, then she'd be able to play and be a VERY happy camper.

Anybody know of some way to do this? Maybe there's another device that she could use that I don't yet know about.

Although primarily the Flight Throttle is used for controlling aircraft in simulations, it is fully macro programmable and can easily be customised to do any number of things in games, etc. This is the one I use and I have programmed it to take the place of the keyboard for non-flying games as well. There is a directional button "china hat" just under the thumb that can be programmed for "wasd" movement controls, for instance.